*


All times are UTC + 1 hour



Post new topic Reply to topic
 [ 15 posts ]  Go to page Previous  1, 2
Author Message
 Post subject: Re: Collaborating Ideas - Long distance board
PostPosted: Sun May 26, 2013 1:01 pm 
Offline
Medium Poster
User avatar

Joined: Tue Jul 19, 2011 5:26 pm
Posts: 192
Location: South Africa
How good is the simulation? Does it take the characteristics of water into account at the correct speeds?

You can maybe try to import these sections into your program and let me know how it compares. For symmetrical (keel and rear wing) I would try e836. For lift (front wing) I would try e904. You can get them and more from here: http://www.ae.illinois.edu/m-selig/ads/ ... abase.html

Then there is a nice article here: http://www.foils.org/hysecdes.pdf

Let me know your progress.


Top
Profile
 Post subject: Re: Collaborating Ideas - Long distance board
PostPosted: Thu May 30, 2013 5:14 am 
Offline
Medium Poster

Joined: Sun Jul 15, 2012 9:32 am
Posts: 80
Location: Tauranga, New Zealand
It takes into account water but does not take into account cavitation
I have now changed the main foil to E908 profile
AR is around 11
still undecided about the rear foil (shape/size)


Attachments:
complete2.jpg
complete2.jpg [ 2.02 MIB | Viewed 863 times ]
Top
Profile
 Post subject: Re: Collaborating Ideas - Long distance board
PostPosted: Thu May 30, 2013 4:15 pm 
Offline
Medium Poster
User avatar

Joined: Tue Jul 19, 2011 5:26 pm
Posts: 192
Location: South Africa
What is the surface area of the main wing?

The rear wing area should be about 1/3 normally, but with your long fuselage you can aim at 1/4 I think.

Why do you have the wing tips curving back and ending sharply? I would suggest just plain elliptical shapes to make manufacturing easier and reduce the risk of injuries.

It looks very beautiful so far, but whether it will work- who knows? Do you ride hydrofoils Bradn, or will this be your first try?


Top
Profile
 Post subject: Re: Collaborating Ideas - Long distance board
PostPosted: Thu May 30, 2013 10:31 pm 
Offline
Medium Poster

Joined: Sun Jul 15, 2012 9:32 am
Posts: 80
Location: Tauranga, New Zealand
Haven't had time to work out area too much study, but roughly sqr( 450^2 + 50^2 + 60^2) x 8

The tips were to try reduce the turbulence at the end of the foil, similar to what is on some plane wings. But I guess in water it might not be necessary.

Until its made, who knows haha
No, this would be my first. :D

Is the rear wing usually symmetrical in profile?


Top
Profile
 Post subject: Re: Collaborating Ideas - Long distance board
PostPosted: Fri May 31, 2013 4:59 am 
Offline
Medium Poster
User avatar

Joined: Tue Jul 19, 2011 5:26 pm
Posts: 192
Location: South Africa
Yip, rear wing should be symmetrical. You want all the lift from the front wing so that your centre of pressure (and thus centre of gravity with riding) are further forward and the rear wing can act as a stabiliser. Obviously the rear wing has no angle of attack (if you can adjust this afterwards to tune the foil it would be good). Front wing angle of attack depends on how much lift the profile makes and how much area it has and what minimum speed you want. I would imagine with AR=11 you want high speeds, so maybe aim for AOA on the front of 0 as well and only rely on the asymmetrical profile for lift?

For the front wing, multiply the wingspan in cm by the average chord length in cm. It should come to around 500cm of front wing area. Rear wing maybe 1/4 of this.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic
 [ 15 posts ]  Go to page Previous  1, 2

All times are UTC + 1 hour


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group